The present invention relates to the field of handling and storage of railway freight wheelsets. This is for use by North American (Canada, United States and Mexico) railroads, freight wheelsets suppliers, wheel shops and transport organizations that move the wheelsets across the North American continent.
Reference: See Appendix FREIGHT WHEELSET ROLLER BEARING DAMAGExe2x80x94TRANSPORTER AND STORAGE PROLBEM report actual AAR rules and regulations and diagrams of present situation.
Present Wheel Transporters
In the same way that automobiles go through tires, railroad cars go through wheelsets. Each year the seven biggest class 1 North American railroads replace about 300,000 freight wheelsets. A wheelset is composed of one axle and one wheel and roller bearing at each end of the axle. Equipment personnel at various line points across North America inspect wheelsets on trains and replace bad order (damaged) wheelsets with good order (new or reconditioned) wheelsets. A damaged wheelset could break apart while the train is in motion and derail the train. The bad ordered wheelsets are sent to wheel shops. The wheel shops recondition the wheelsets and then send them back for use at the line points.
Wheel transporters move wheelsets between the line points and the wheel shops. These are rail cars that were modified to carry only wheelsets. For example, in 1996 CN had a fleet of 150 wheel transporters for freight wheelsets. These wheel transporters carried up to 44 wheelsets at one time. The wheelsets are loaded in two rows on the transporters. The first row consists of 23 wheelsets placed directly on the wheel transporter. A second row of 21 wheelsets lies on top of the first row. Two interlocking tiers of wheelsets make up each row.
The wheelsets are not tied down to the wheel transporters. Steel clamps tie the last four wheelsets at both ends of the car together. The forces that the wheelsets experiences during switching (moving individual cars to form a train consist or to spot at a location) or while the train is in motion could cause them to displace if the four end wheelset were not tied together. Together they act as a unit to block the other wheelsets from moving.
The AAR Wheel and Axle Manual states the following:
Section 1
Rule 1J6 Wheels mounted with roller bearings in place must be arranged when stored so the wheel flanges cannot strike either the roller bearing housing or the body of the adjacent axle. FIG. 4.52 in the Appendix illustrates a track arrangement for wheel and axle assemblies having roller bearings. When this arrangement is not available, assemblies should be stored one behind the other on single tracks.
Rule 1J7 The same precautions must be used in placing mounted wheels on a car for shipment. In addition they shall be securely blocked to prevent rolling and end sliding. Details of approved methods are given in the current issue of AAR Loading Rules.
Section 3
Rule 3B5 Special wheel cars should be provided for the shipment of mounted wheels between wheel shops and repair points. AAR Loading Rules illustrate approved methods of loading. Such cars have proved to be more reliable than the use of blocking in preventing axles from becoming damaged in transit. Wheel rack arrangement for shipping mounted wheels is illustrated in the Manual of Standards and Recommended Practices.
Together rules 1J6 and 1J7 state that wheel flanges must not strike the roller bearing of an adjacent wheelset while they are being moved on wheel transporters. The CN wheel transporter design uses the four end wheelsets that are tied together to block the other wheelsets from displacing when the transporter experiences normal forces during switching or train movement. The parts of the wheelsets that come in contact when they are blocked by the four end wheelsets are wheel flanges to roller bearings. This goes against rules 1J6 and 1J7.
A loading arrangement on an open top rail car must pass a number of tests before it becomes an approved method in the AAR Open Top Loading Rules. One of the tests is an impact test. Impact tests are like automobile crash tests using crash test dummies. Automobile crash tests deals with the safety of passengers. AAR impact test determines proper loading methods to ensure that the load being transported is not damaged.
In an impact test a number of rail cars, with a gross total weight of 250,000 pounds, are coupled together. These cars are placed on one track with both their hand and air brakes filly applied. In effect these rail cars act like a wall. A locomotive pushes the rail car with the test loading arrangement toward this wall of parked rail cars. At a certain speed the locomotive releases the test car so it hits the wall on its own. The test car must hit this wall at 4 miles per hour. After the impact the load is inspected. If everything is okay the test car must impact the wall at 6 miles per hour. If the load passes this impact a third impact at 8 miles per hour is performed. The same end of the test car impacts the wall during the 4, 6 and 8 miles per hour impacts. This ensures that the impact forces on the load are in the same direction. If the test car passes these three impacts then one more impact is made. The test car is turned around and pushed toward the wall so that the opposite end of the car hits the wall at 8 miles per hour. The load now experiences high forces in the opposite direction to those experienced in the first three impacts.
If the present wheel transporters used by CN and other North American railroads were to under go such an impact test, they would fail the test because contact would be made between roller bearings and adjacent wheel flange. The result of impact tests done with wheel transporters loaded with bad order wheelsets clearly shows that if good order wheelsets had been used, they would have been damaged. A loading arrangement that cannot be tested with new or reconditioned wheelsets should not be used to transport new and reconditioned wheelsets.
Unlike a passenger train, the ride of a freight train is not a smooth ride. Therefore, it is likely that the wheel flanges will hit the roller bearing of an adjacent wheelset often during transportation between wheel shops and line points. When the transporters are switched the flanges will contact the roller bearings with even greater force. This constant contact between wheel flange and roller bearing can damage the roller bearing internally. This damage could eventually lead to a hot box and a major derailment.
Wheelset Storage Racks
Constant replacement of bad order wheelsets requires the storage of wheelsets at line points and wheel shops. North American railroads store wheelsets in the same arrangement as on wheel transporters. Each row consists of two interlocking tiers of wheelsets. The wheelsets are piled several rows high depending on how busy the line point is. Unfortunately this is not the approved method of storing roller bearing wheelsets shown in FIG. 4.52 in Section 4 of the AAR Wheel and Axle Manual which ensures that the roller bearing is never in line with the wheel flange of an adjacent wheel (see appendix).
Rule 1J6 of the AAR Wheel and Axle Manual states that
xe2x80x9cFIG. 4.52 in Section 4 of the AAR Wheel and Axle Manual illustrates a rack arrangement for wheel and axle assemblies having roller bearings.xe2x80x9d
Although wheel shops with overhead cranes would not have any problems stacking the wheelsets in the approved AAR manner, line points that only use forklifts would have problems. The flanges of the wheelsets, in the approved loading method for roller bearing wheelsets, are never in line with roller bearings and therefore contact is not made.
Rule 1J6 also states that
xe2x80x9cWhen this arrangement is not available, assemblies should be stored one behind the other on single tracks.xe2x80x9d
This also ensures that wheel flanges are never in line with roller bearings since there is no tiers of interlocking wheelsets, but only some locations will use this method.
The actual method used to store wheelsets in many locations by North American railroads and wheel shops allows for direct contact between roller bearing and adjacent wheel flange. Wheelsets are placed or removed from storage sites using overhead cranes (at wheel shops) or by forklifts (at line points). Unless employees are extremely careful while placing or removing roller bearing wheelsets from storage, the roller bearing will be struck by wheel flanges and possibly damaged. Again rule 1J6 is violated and another concern for hot boxes.
Hot Boxes
Consider a freight car traveling across Canada from Halifax to Vancouver, a 6,050 kilometer distance. Also, this car is equipped with roller bearing wheelsets and 36xe2x80x3 diameter wheels. Assume that the car""s speed across Canada is 80 kilometers per hour (50 miles per hour). The wheels of this car would make over 2.1 million revolutions at a speed of 7.7 revolutions per second. This car could make up to 20 such trips in one year.
To sustain such use the internal components of the roller bearing must be in good condition. Internal grease must always be present to keep these components lubricated. Any damaged component would damage another component that it is in constant contact with. Damaged seals could let the grease leak out of the roller bearing or let particles enter. Running the bearings without grease is like running an automobile engine without oil. Foreign particles that may enter may damage internal components. Damaged internal components may break up very quickly after continuous use. The friction between damaged internal components or the loss of grease would eventually increase the internal temperature of the roller bearings tremendously during a typical trip causing a hot box. A hot box refers to a roller bearing that is overheating.
If a hot box goes undetected the internal temperature could rise to a point where the roller bearing literally melts away. Then the wheelset would collapse under the moving train and cause a derailment. This is such a serious problem that hot box detectors are located at numerous points across the rail system. The hot box detector is a device with a heat sensor. It is placed at the side of a track and at the same level of a moving train""s wheels. When a train passes by a hot box detector and one of its wheels has a hot box a central location overseeing all lines receives a signal from the hot box detector. The operator at this location obtains a readout that indicates exactly which axle on the train has the hot box. He then radios the crew of the train with the information. The train stops and the crew investigates the suspect hot box. In case a train""s route does not take it past a hot box detector the train crew routinely walk along the train to see that everything is in order. They usually have some device like a temperature indicating crayon to check for hot boxes.
Each year the major North American railroads experience anywhere between 200 to 350 hot boxes per year on each of their lines. With all the precautions taken some hot boxes are not detected and result in burnt out journals and derailments.
On Nov. 10, 1979, a train derailed in Mississauga, Ontario. The cause was a hot box. Some of the cars that derailed were carrying dangerous commodities. Cars loaded with propane exploded and one of the tank cars carrying the deadly gas chlorine suffered a 2xc2xd foot diameter hole in its shell. The danger of deadly chlorine gas escaping caused the evacuation of nearly a quarter of a million people from their homes or businesses.
The constant contact between adjacent wheel flanges and roller bearings when good ordered wheelsets are placed or removed from storage racks or moved by wheel transporters can damage the internal components of the roller bearing. This could lead to a hot box and a potentially serious derailment. This is because contact between the wheel flange and the roller bearing is only at a single point and not over a large area. To fully understand the difference between single point contact and contact over a large area, consider the difference in pain felt by a foot stepped on by 200 pound person wearing high heel stiletto shoes (single point contact) or wearing flat running shoes (contact over a large area). Since blows at a single point are severe, the AAR conceived of rules 1J6 and 1J7 of the Wheel and Axle Manual. Rules not complied with by wheel transporters or storage racks.
One way to verify if a problem really exists is to gauge the roller bearing manufacturer""s confidence in their product. Are they ready to say that their bearings can take the constant hitting from adjacent wheel flanges during delivery to line point on wheel transporters? They may be liable for another Mississauga derailment due to a hot box if they say yes.
The most important aspect in the AAR rules for the safe handling of wheelsets while they are being moved or stored is that the roller bearing or axle of a wheelset must not come in direct contact with the wheel flange of an adjacent wheelset. This is because contact is at a single point, which could result in unseen internal damage. If a damaged wheelset is applied under a rail car, this damage could lead to a hot box and an eventual derailment if not caught in time. Unfortunately, the method used to store and move wheelsets across North America by the railroads, wheel shops, wheelset suppliers and other transport companies allow for the direct contact between roller bearing and adjacent wheel flange. These forces on the roller bearing while the wheel transporter is moved, humped or flat switched can be considerable. Also, since there is direct contact between roller bearing and adjacent wheel flange the methods presently used are illegal.
This invention shows different ways that wheelsets may be transported so that there is no contact between roller bearing and an adjacent wheel flange. This is done by (a) applying roller bearing protectors, (b) applying axle protectors, (c) shifting the wheelsets on the wheel transporter so that roller bearing and adjacent wheel flange never come in contact, or (d) restricting the movement of adjacent wheelsets relative to one another while in transport with the use of wheelset stoppers or axle spacers.
This invention also shows that if a roller bearing or axle protector is used, then contact between roller bearing and adjacent wheel flange will never occur at the storage areas. The present stacking method used by the railroads, wheel shops and wheel suppliers, which does not use a roller bearing protector, is only approved for friction bearing wheelsets and therefore illegal for roller bearing wheelsets. The approved roller bearing stacking method is not used since it causes handling problems at storage areas that are not equipped with overhead cranes and use forklifts. With the simple addition of a roller bearing protector, the present stacking method could then be approved for roller bearing wheelsets.